Modern pollen deposition in wetlands of Majuli Island and its implication to decipher palaeoflood episodes in northeast India

Abstract

The present study is the first attempt from any Indian wetland, where palynological data is assessed to understand the flooding histories of the Sakali and Duboi wetlands in the Majuli River Island, a part of the Indo-Burma hotspot. Palynological analyses of surface soil samples from these wetlands were carried out in order to explore the flooding histories of this island. The presence of extra-local taxa such as Rhododendron, Tsuga and Castanopsis, in the Sakali wetland is strongly suggestive of river water transportation and flooding on the Majuli Island in the recent past. In contrast, dominance of local arboreal taxa and low abundance or absence of extra-local pollen taxa in the Duboi wetland does not indicate flooding. Correspondence analysis (CA) was applied on the present dataset to reveal possible correlations between the surface samples of the wetlands and the major group of palynotaxa. The CA successfully discriminated the samples from the two wetlands and also marked strong correlations between flood indicators extra-local taxa with the samples of the Sakali wetland and local arboreal elements with the Duboi samples. The present result will not only provide a baseline for future palaeovegetation and palaeoclimate reconstructions, but will also help in deciphering palaeoflood episodes from these wetlands.